First let's isolate the sin(x) term
4sin(x) - 4 = 0
4sin(x) = 4
sin(x) = 1
Now use the unit circle and you'll see that the only solution in the interval [0,2pi) is x = pi/2
If you want to ignore the restriction and consider all solutions, then x = (pi/2) + 2pi*n where n is any integer